1. Field of the Invention
The invention relates generally to computer architectures and, more particularly, to a method and an apparatus for a scaleable touch panel controller.
2. Description of Related Art
Touch panels are an increasingly popular method of entering information into a computer system. One particular technology of touch panels generally utilizes a screen comprising conductive leads arranged vertically and horizontally terminating at an X-resistance and a Y-resistance element, respectively. When the screen is touched, the conductive leads contact each other, creating an electrical path for current to flow. The position is generally determined by detecting the relative level of voltage via analog-to-digital (A/D) converters. A/D converters, however, generally require a stable power supply and linear circuit techniques, and, therefore, are not practicable for devices that utilize low-voltage linear amplifiers or scaleable-voltage amplifiers, such as some Personal Data Assistants (PDAs).
Therefore, there is a need for a method and an apparatus for providing a digital interface to a touch panel sensor.
The present invention provides a method and an apparatus for determining the contact position on a touch panel sensor. The method and apparatus measures the elapsed time that passes for a circuit between two connectors to discharge from its peak value to a predetermined threshold. The contact position is determined by measuring the elapsed time for circuit to discharge between differing points.